Thread: Turbo onto 4jb1

Should do. What is up with the 4JX1? Engine damage or just head/injectors? There may be more parts you can get.

Beware of the 4JX1, I was a mechanic at holden when they were around. They are by far the worst engine I have ever worked on and are plagued with problems even to this day.

I very much doubt that the manifold will be the same as the cyl heads are completely different. The IHI turbos that they had fitted use to self destruct regularly and the early ones had a very short front on them where the intake hose clamps on. As a result the intake hose use to come off regularly and the turbo and engine would end up dusted.

The turbos fitted to 4BT1T's (2.8t rodeo), 4JG2T's (3.1t jackarooo) and 4JH1T (3.0 rodeo but with electronic inj pump) would be a safer option and the manifolds may even swap over as they are the older style 8 valve cyl head.

Not sure if you are aware that your N/A 2.8 4JB1 will have a higher compession ratio than the 2.8T 4JB1T. This means that you will probably need to run a very low boost on the turbo. Your N/A injection pump will probably not be suited for a turbo engine either.

I would find a complete engine in a wreck, later 4JB1T would be best as they go way better than the earlier ones.

Good luck

Dave

The 4JX1 was one of the first unit injection diesels ever used in a passenger car. Apparently very sensitive to oil type. I could imagine turbo failure being a direct result of injection problems and not the fault of the turbo itself.

They are all IHI RHB5/RHF5 turbos on the 4JB1, 4JG2 and 4JX motors. Essentially the same core units, just running harder on the 4JX motors.
All turbos for Isuzu passenger cars and vans - Applications - TurboMaster

I would like to see if the four valve head the 4JX used could be converted to mechanical injection easily. It would give you a very fast and smooth compact engine with better strength than most other 3 litre diesels. Owners of good 4JX motors were reporting excellent fuel economy. Like under 7 litres/100km on a highway run.

The 4JB1 doesn't have a high compression ratio.

Yes they were the first unit injector on a passsenger vehicle. It was a Caterpillar design from memory and the unit injecotrs were not quite the same as the TD5 setup.

They were a hydrolic unit injector (HUI). which meant that the injecotr was supplied its high pressure from a high pressure oil pump which also related to the starting problems you refer to and oil grades etc.

And yes the turbo pressures on a 4JX1 were about 16-17psi whereas the other engines mentioned where all under 10, about 7 from memory.

The turbos on 4JX1 were heavily affected by exhaust temps and quite often found the exhaust turbine sitting down in the exhaust somewhere.

The injecotrs and their o-rings were prone to failure with a number of fixes being provided by Holden / Isuzu.

I do remember a number of nozzles falling off injectors or simply failing which often resulted in holes burnt in pistons or the nozzle being smashed up in the cylinder (all bad).

Fitting mechanical injectors to the cyl head would be more than difficult due to the oil and fuel galleries in the cyl head and would result in a huge loss of power anyways.

Do yourself a favour and just stay away from 4JX1's. They make TD5's look totally awesome.

The technology allowed for great power and fuel economy as you mentioned however you don't have to go far to find a horror story or an unhappy customer. I think it would be safe to say that there wouldn't be a holden mechanic in the country that would tell you to buy one of these engines.

It was a great shame for these engines to be fitted to Jackaroos as they are / were a great car and super reliable. The 3.1Td (4GJ2t) in the model before the 4JX1 is a far better option but hard to find and a bit thirsty on the juice, and the V6's were also very good but very thirsty.

Cheers

Dave

I'm thinking the high EGT's are the cause of injector tips leaving, pistons melting and turbos blowing. Just like the nissan ZD30.

A mechanical injection 4 valve engine can produce the same power, torque and fuel economy as an EFI version. It just can't meet the same emissions levels and will likely be a bit noisier. There have been a couple of attempts at building mechanical direct injection 4 valve toyota engines from 1KZ and 1KD parts. One successful, one still in progress.


These were the only specs I can find on a 4JX powered trooper.
2002 ISUZU Trooper 3.0 TD Citation
Luckily they match the JDM bighorn specs. (mistakes abound online)
http://specs.amayama.com/specs-isuzu...01-july/13449/

160hp is 118kw, 245 ft-lb is 330Nm.

Originally Posted by Dougal

Should do. What is up with the 4JX1? Engine damage or just head/injectors? There may be more parts you can get.

The head is buggered and he has sold the block so I thought I may be able to use the turbo but it seems not.
So can the 4j na be turboed like the 4b na or is it not just not feasible?

Originally Posted by 123rover50

The head is buggered and he has sold the block so I thought I may be able to use the turbo but it seems not.
So can the 4j na be turboed like the 4b na or is it not just not feasible?

Of course the 4JB1 can be turbocharged. Why can you not use the turbo from the 4JX?

It seems I can use the turbo but not the manifolds.
Conflicting opinions on the compression and the NA pump not being suitable.